LI. Measurements on Alloy-Type Germanium. Transistors and their Relation to Theory

Abstract

Two methods for the accurate determination of the current amplification factor, ∞ of junction transistors are described and are applied to a germanium p-n-p alloy transistor. On the basis of an injection ratio of unity, the frequency dependence of xi is compared with the theoretical variation of the base transport factor, β obtained from the equations of the one-dimensional minority-earrier-diffusion theory. The comparison confirms the applicability of this theory and further confirmation is obtained by considerations of the detailed variation of the emitter-base impedance with emitter current. The results are then used to show that the mobility of holes in n-type germanium varies as T^{− 2.3} and that the effective diffusion constant is doubled in going from small to large emitter currents in agreement with an extension of the above theory. Three methods for estimating the effective base thickness are described; the values obtained are in agreement